The present invention relates to closing the ends of tubular fabric and more particularly to closing the ends of tubular fabric by constricting the fabric and then severing and sealing the constricted portion of the fabric.
Various attempts have been made to form end closures in tubular fabric with improved production that does not require complex or time consuming operations and mechanisms. Efforts have been directed to this in the knitting field in particular, such as in the production of circular knit hosiery where toe closing of hosiery tubes has traditionally involved difficult and expensive looping operations or separate seaming operations. Obviously it would be advantageous to have an automatic method and apparatus for closing fabric tubes integral with a knitting machine so that tubular articles could be discharged from the machine with ends already closed and without requiring any additional time or operation in regard to end closing.
An example of a prior attempt to close the end of a tubular fabric while it is on a circular knitting machine is disclosed in Currier U.S. Pat. No. 3,340,707, dated Sept. 12, 1967, which teaches twisting of a suspended portion of tubular fabric in relation to the main body of the fabric to constrict by twisting to a small hole size and then knitting the twisted fabric to the body to retain the substantially closed end configuration. This results in a bulky accumulation of fabric due to the twisting and the two thicknesses of fabric required for the closing. As a result this operation has not met with notable commercial acceptance.
Another example of a prior attempt to close the end of a tubular fabric on a knitting machine is disclosed in Colton U.S. Pat. No. 3,550,402, issued Dec. 29, 1970, which shows an operation of questionable operability wherein in one form tubular fabric is restrained at a spacing from knitting needles so that the fabric is twisted and backs up to a centrally located heating element that supposedly fuses the twisted fabric to form a closure, and in another form the heating element is advanced from the side of the restrained fabric. In either form it is not apparent that a reliable and effective toe closure can be obtained for production purposes.
In contrast, the present invention, as more fully explained hereinbelow, provides a simple, efficient, reliable and effective method and apparatus for forming end closures in tubular knitted articles without any variation in the knitting procedure, without any complicating fabric manipulation, or configuration, and results in a strong yet relatively unnocticeable closure core connecting the yarns of the fabric into a closed end.